Horizontal power piston engines are especially designed for oilwell pumping service and are the primary power source for operating oilfield pump equipment. Such engines are designed for slow speed operation in a wide variety of climates, ranging from hot arid to arctic environments. Conventional horizontal power piston engines are designed for continuous operation with minimum maintenance at a maximum rpm range of about 600 to 800 rpm.
Most conventional horizontal power piston engines are designed for liquid cooling by circulation of liquid coolant, such as water or water and antifreeze mixtures, within internal water jackets contained by the engine block and cylinder head. Thus, conventional liquid cooled horizontal power piston engines employ radiator units by which the temperature of the liquid coolant and, hence, the engine temperature, is regulated.
Although such engines are designed for minimum maintenance, the necessity of cooling such engines by liquid circulation through water jackets to a radiator unit introduces an inherent weakness to the engine design in terms of maintenance and potential down time of the engine. Namely, when a liquid cooling system is employed, proper operation of the engine can only be insured by proper operation of the liquid cooling system. Proper coolant composition suitable to the environment in which the engine is to be used must be provided, meaning an operator must monitor the cooling fluids periodically for proper antifreeze and corrosion inhibitor levels. Additionally, radiator units are prone to develop leaks and to develop corrosion on the cooling cores of the radiators which inhibit proper heat exchange operation. Further, makeup coolant must be added to the liquid cooling system periodically to maintain a proper coolant level and it is difficult to add makeup coolant to a horizontal power piston engine while the engine is in operation.
Heretofore various designs and means for air cooling of internal combustion engines have been employed or suggested. Some air cooling designs are functionally related to the intended use of the engine--such as an airplane engine or motorcycle engine--and employ air cooling design features, such as a plurality of heat exchanging fins secured to the cylinder wall across which air passes while the engine is in motion, which features would not be effective for air cooling of a stationary engine. Various designs have been proposed for air cooling internal combustion engines which employ relatively unrestricted passages or chambers about the cylinders specifically designed for the passage of air, as opposed to liquid circulation. Hence, Marsh, U.S. Pat. No. 1,330,207 and Till, U.S. Pat. No. 2,315,462 employ hoods of specific design which jacket the engine cylinders to create relatively unobstructed passageways adjacent to the cylinder walls through which air is drawn by a vacuum producing means operated by the engine exhaust system.
Others have suggested air cooling means which utilize the water jackets of an engine designed for liquid cooling as the passages through which air is drawn for air cooling. Sauer, U.S. Pat. No. 2,188,444 employs an air scoop to collect and direct air into the water jackets of an automobile engine and connects the outlet side of the water jacket to a turbine, operated by the engine exhaust gases, to draw a vacuum on the water jacket. The combined action of supplying air to the jacket under the elevated pressure via the air scoop in conjunction with drawing a vacuum on the outlet side of the water jacket by turbine action is said to permit a sufficient circulation of ambient air within the engine water jacket to achieve proper cooling. In an earlier proposal, by Brittain, U.S. Pat. No. 1,800,927, the same kind of push-pull system was suggested for an automobile engine, but Brittain used an air blower to supply pressurized air to the inlet of the water jacket. Again, in the Brittain proposal provisions for supplying pressurized inlet air and evacuating outlet air had to be employed in order to secure adequate air circulation within the water jacket of the engine for proper cooling.
None of the above proposals are suitable for application to a horizontal power piston engine of conventional design. Most horizontal power piston engines are of a single cylinder design and operate from a stationary position. Since such engines operate on a single cylinder, the engine exhaust gases cannot be utilized to operate a vacuum device for drawing air from about the water jacket because this would disrupt the proper flow of exhaust gases from the combustion chamber and adversely effect engine operation. Likewise, since the engine operates in a stationary piston, it has no forward momentum through the atmosphere by which air may be scooped into the engine or caused to pass through the water jacket about the cylinder wall of the engine. Heretofore, no design has been proposed for a horizontal power piston engine by which such engine could be air cooled.
A need exists for a horizontal power piston engine design which eliminates the problems inherent with cooling such engines by liquid cooling systems. A horizontal power piston engine of a design suitable for cooling by ambient air is highly desirable, especially in arctic climates where liquid coolant systems are prone to freeze up and in acid climates where such systems are prone to boil over. Likewise, it would be desirble to have a means by which conventional horizontal power piston engines designed for liquid cooling could be modified to cooling by ambient air.